This invention relates to commodity metering systems, and is more particularly but not exclusively concerned with a multi-rate prepayment electricity metering system.
In United Kingdom Patent Application No. 8401932 (Publication No. 2153573A), there is described and claimed a prepayment electricity metering system in which an electronic key containing a memory co-operates with a receptacle in an electricity meter to control the supply of electricity to a consumer. It is an object of the present invention to provide a commodity metering system based on such an electronic key and receptacle and having enhanced facilities, either in addition to or instead of a prepayment facility.